A system for dc input control of a photovoltaic system

Abstract

The application discloses a system for direct current input control of a photovoltaic system, a switch module includes a switch group, a first switch, a second switch and a power switch tube, the switch group includes a plurality of third switches connected in series with each other; one end of the power switch tube is connected with the first third switch in the switch group, the other end of the power switch tube is connected with the first switch and the first third switch in the plurality of first switches respectively, the other end of the power switch tube is connected with the second switch and the last third switch in the switch group respectively, the first switch and the second switch are connected with a DCDC / DCAC inverter module respectively, the DCDC / DCAC inverter module is connected with a power grid module; a signal acquisition module is connected with a control module, the control module is connected with a driving circuit module, and the driving circuit module is connected with the power switch tube, the first switch, the second switch and the plurality of third switches respectively. The application enhances the safety performance and reliability of the system.

Description

Technical Field

[0001] This invention relates to the field of DC input control technology for photovoltaic power generation, and in particular to a system for DC input control of photovoltaic systems. Background Technology

[0002] With the development of technology and the implementation of national policies for new energy development, photovoltaic power generation has gained a significant share of new energy sources and is attracting increasing attention. Its application scale is continuously expanding, but this also brings some problems. Currently used photovoltaic power generation systems first connect several photovoltaic modules in series outside the inverter, then connect the DC interface to the inverter and connect it to the grid. Figure 1 As shown, if one of the components in the series connection fails, the DC input system may not be able to operate, and thus the grid may be disconnected. Furthermore, direct connection of high voltage to the inverter will pose many safety hazards. At the same time, when the grid connection system fails, it is also necessary to disconnect the connection between the DC input and the inverter system in a timely manner to further ensure the safety of personnel and equipment. Therefore, this invention was developed. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of the aforementioned technologies by designing a system for DC input control of photovoltaic systems, the specific structure of which is as follows.

[0004] The present invention discloses a system for DC input control of a photovoltaic system, comprising a switching module, a DC-DC / DC-AC inverter module, a grid module, and a CPU control module;

[0005] The switching module includes a switch group, a first switch, a second switch, and a power switching transistor. The switch group includes multiple third switches connected in series.

[0006] One end of the power switch is connected to the first third switch in the switch group, and one end of the power switch is connected to the first switch and the first first switch among a plurality of first switches. The other end of the power switch is connected to the second switch and the third switch at the end of the switch group. The first switch and the second switch are connected to the DC-DC / DCAC inverter module, and the DC-DC / DCAC inverter module is connected to the grid module.

[0007] The CPU control module is connected to the power switch, the first switch, the second switch, and multiple third switches respectively. When it receives a voltage or current signal and determines that it matches the set turn-on or turn-off threshold, it controls the switching state of at least one of the power switch, the first switch, the second switch, and multiple third switches.

[0008] As preferred, the plurality of photovoltaic components are further included, and the positive and negative poles of each third switch are respectively led out electric connection lines, and the two electric connection lines on the third switch are connected with a corresponding photovoltaic component.

[0009] As preferred, when the two electric connection lines on all the third switches are connected with photovoltaic components, or only the two electric connection lines on part of the third switches are connected with photovoltaic components, and the two electric connection lines on the rest of the third switches are short-circuited, the steps of turning off and turning on the direct current input are as follows:

[0010] When the direct current input is turned off, the CPU control module receives a turn-off signal and controls the switch group, so that the power switch tube is turned on, the first switch and the second switch are turned off, and then the power switch tube is turned off, so as to turn off all the third switches, thereby completing the turn-off of the direct current input;

[0011] When the direct current input is turned on, the CPU control module receives a turn-off signal and controls the switch group, so that the power switch tube is turned on, the first switch and the second switch are turned off, and then the power switch tube is turned off, so as to turn on all the third switches, thereby completing the turn-on of the direct current input.

[0012] As preferred, the first switch, the second switch and the plurality of third switches adopt contactors or relays.

[0013] As preferred, the power switch tube adopts an IGBT switch tube or a GTO switch tube or a MOSFET switch tube or a BJT switch tube.

[0014] Compared with the prior art, the system for direct current input control of a photovoltaic system designed in the application has the following beneficial effects:

[0015] 1. The application solves the problem that the system cannot run due to the failure of a traditional external group string, and has the advantage of multiple power inputs; solves the problem of automatic protection of the direct current input end when the inverter fails, and further enhances the safety performance and reliability of the system.

[0016] 2. The application uses each third switch to be connected with a corresponding photovoltaic component to play a protection function, and the third switches are connected in series with each other, and each third switch is a single-phase low-voltage input, which changes the traditional group string high-voltage input mode and improves the reliability and safety of the system.

[0017] 3. When not all the third switches are connected with photovoltaic components, the two electric connection lines on the third switches not connected with photovoltaic components can be short-circuited for protection, so different input power levels can be converted, and accidents can be avoided;

[0018] 4、When one or more photovoltaic modules are faulty, the faulty DC input port can be short-circuited, while the non-faulty photovoltaic modules are normally connected and run, and the system runs normally, and different power input can be converted;

[0019] 5、The circuit structure and working mode of the first switch, the second switch and the power switch tube have the connection of the DCDC / DCAC inverter module and the photovoltaic power generation end, which plays a protection function, and the switching sequence of them avoids the switching damage phenomenon. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of a traditional technical structure;

[0021] Figure 2 is a schematic diagram of a system structure of the present application (one);

[0022] Figure 3 is a schematic diagram of a system structure of the present application (two);

[0023] Figure 4 is a schematic diagram of a system shutdown process of the present application;

[0024] Figure 5 is a schematic diagram of a system startup process of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0026] Embodiment:

[0027] As Figures 2-5As shown, the system for direct current input control of a photovoltaic system described in the embodiment comprises a switch module, a DCDC / DCAC inverter module, a grid module, and a CPU control module; the switch module comprises a switch group, a first switch, a second switch, and a power switch tube, the switch group comprises a plurality of third switches connected in series; one end of the power switch tube is connected to the first third switch in the switch group, one end of the power switch tube is connected to the first switch and the first third switch in the plurality of first switches respectively, the other end of the power switch tube is connected to the second switch and the last third switch in the switch group respectively, the first switch and the second switch are connected to the DCDC / DCAC inverter module respectively, and the DCDC / DCAC inverter module is connected to the grid module; the CPU control module is connected to the power switch tube, the first switch, the second switch, and the plurality of third switches respectively, and when a voltage or current signal is connected and the value is consistent with the set on threshold or off value, the CPU control module controls the on / off state of at least one of the power switch tube, the first switch, the second switch, and the plurality of third switches; wherein each third switch serves as a direct current input port of a photovoltaic module, and the switch module and the DCDC / DCAC inverter module form an inverter device.

[0028] Preferably, the first switch, the second switch, and the plurality of third switches adopt contactors or relays; the power switch tube adopts IGBT switch tubes or GTO switch tubes or MOSFET switch tubes or BJT switch tubes.

[0029] Based on the above system, a plurality of photovoltaic modules are connected, the positive and negative poles of each third switch are connected to the electric connection lines respectively, and the two electric connection lines on the third switch are connected to a corresponding photovoltaic module; when all the two electric connection lines on the third switch are connected to the photovoltaic module, or only part of the two electric connection lines on the third switch are connected to the photovoltaic module and the two electric connection lines on the rest of the third switch are short-circuited, the steps of turning off and turning on the direct current input are as follows:

[0030] When the direct current input is turned off, the CPU control module receives the off signal and controls the switch group so that the power switch tube is turned on, the first switch and the second switch are turned off, and then the power switch tube is turned off, thereby prompting all the third switches to be turned off to complete the turning off of the direct current input;

[0031] When the direct current input is turned on, the CPU control module receives the on signal and controls the switch group so that the power switch tube is turned on, the first switch and the second switch are turned on, and then the power switch tube is turned off, thereby prompting all the third switches to be turned on to complete the turning on of the direct current input.

[0032] The system for direct current input control of a photovoltaic system described in the embodiment has a plurality of low-voltage single-phase direct current input ports arranged inside the inverter device, and each port has a third switch connected in series inside the inverter device; when the inverter device ports are connected to photovoltaic modules, all the third switches are closed by controlling the driving circuit, and then output to the DCDC / DCAC inverter module through the first switch S1 and the second switch S2, and then enter the power grid.

[0033] When the plurality of photovoltaic modules are not all connected to the direct current input ports of the inverter device, the unused part of the direct current input ports of the inverter device is short-circuited for protection, as shown in Figure 2 , which can also convert different input power levels and avoid accidents.

[0034] The plurality of third switches arranged inside the inverter device are connected to the plurality of photovoltaic modules, and the plurality of third switches are connected in series; on the one hand, when one or more photovoltaic modules fail, the failed direct current input port can be short-circuited, and the normal connection of the non-failed photovoltaic modules is not affected; on the other hand, each direct current input port is a low-voltage single-phase input, which is different from the traditional photovoltaic structure that is connected in series and then high-voltage input to the inverter device; compared with the plurality of single-phase low-voltage inputs, the high-voltage input is prone to danger, has high damage to the device, reduces the service life of the device, and if a photovoltaic module fails, the circuit composed of the series-connected modules cannot operate, so the present application has high reliability and strong safety.

[0035] In addition, by connecting a power switch tube Q in parallel, the first switch S1 and the second switch S2 are connected to the input end of the DCDC / DCAC inverter module, and the first switch S1, the second switch S2 and the power switch tube Q have a protection function when performing direct current output.

[0036] The present application is not limited to the above-mentioned best embodiment, and anyone can derive other various forms of products under the inspiration of the present application, but regardless of any changes in shape or structure, any technical solution with the same or similar technical solution as the present application falls within the protection scope of the present application.

Claims

1. A system for photovoltaic system DC input control, characterized by, The switch module, the DCDC / DCAC inversion module, the grid module and the CPU control module are included. The switch module includes a switch group, a first switch, a second switch and a power switch tube, and the switch group includes a plurality of third switches connected in series. One end of the power switch tube is connected with the first third switch in the switch group, and the other end of the power switch tube is connected with the second switch and the last third switch in the switch group, respectively. The CPU control module is connected with the power switch tube, the first switch, the second switch and the plurality of third switches, respectively. When the voltage or current signal is connected and the set opening threshold or closing threshold is consistent, the CPU control module controls the switch state of at least one of the power switch tube, the first switch, the second switch and the plurality of third switches. The plurality of photovoltaic components are further included. When all the two electric connection lines of the third switches are connected with the photovoltaic components, or only part of the two electric connection lines of the third switches are connected with the photovoltaic components and the rest of the two electric connection lines of the third switches are short-circuited, the steps of closing and opening the direct current input are as follows:

2. A DC input control system in a photovoltaic system as claimed in claim 1, wherein, When the direct current input is closed, the CPU control module receives the closing signal and controls the switch group so that the power switch tube is turned on, the first switch and the second switch are closed, and the power switch tube is turned off, thereby promoting all the third switches to be turned on to complete the closing of the direct current input.

3. A system for DC input control of a photovoltaic system according to claim 1 or 2, characterized in that, When the direct current input is opened, the CPU control module receives the closing signal and controls the switch group so that the power switch tube is turned on, the first switch and the second switch are closed, and the power switch tube is turned off, thereby promoting all the third switches to be turned on to complete the opening of the direct current input.

4. A system for DC input control of a photovoltaic system according to claim 1 or 2, characterized in that, The positive and negative poles of each third switch are connected with the electric connection lines, respectively. The first switch, the second switch and the plurality of third switches are contactors or relays. The power switch tube is an IGBT switch tube, a GTO switch tube, a MOSFET switch tube or a BJT switch tube.

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